fix(routermon): fix receiver startup, logging config, and JS template escaping

- Remove SO_REUSEADDR from UDP socket so only one gunicorn worker binds
  port 5514 (second worker intentionally gets EADDRINUSE and skips)
- Add print() fallback for bind confirmation/errors so startup is visible
  even when Django logging config is not fully set up
- Fix duplicate LOGGING dict in settings.py: second assignment was
  overriding the first and removing the root logger handler, silently
  swallowing all routermon/core startup logs
- Add sys.stderr fallback in core/apps.py ready() for startup exceptions
- Fix JS SyntaxError: {{ top_domains_json }} needs |safe filter since
  Django auto-escapes quotes to " inside script tags

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

core/apps.py

@@ -89,4 +89,6 @@ class CoreConfig(AppConfig):
             )
             logger.info("routermon: scheduled cleanup job (every 6h)")
         except Exception as exc:
+            import sys
+            print(f'routermon: startup error (non-fatal): {exc}', file=sys.stderr, flush=True)
             logger.warning("routermon: startup error (non-fatal): %s", exc)

core/settings.py

@@ -232,21 +232,8 @@ CRAWL4AI_ENABLED = os.environ.get('CRAWL4AI_ENABLED', 'True').lower() in ('true'
 BUILD_TIME = os.environ.get('BUILD_TIME', '')
 BUILD_VERSION = os.environ.get('BUILD_VERSION', '')
 
-# For debugging
-LOGGING = {
-    'version': 1,
-    'disable_existing_loggers': False,
-    'handlers': {
-        'console': {
-            'class': 'logging.StreamHandler',
-            'level': 'DEBUG',
-        },
-    },
-    'loggers': {
-        'links': {
-            'handlers': ['console'],
-            'level': 'DEBUG',
-            'propagate': True,
-        },
-    },
+LOGGING['loggers']['links'] = {
+    'handlers': ['console'],
+    'level': 'DEBUG',
+    'propagate': False,
 }

routermon/receiver.py

@@ -54,15 +54,19 @@ def start_receiver(port: int):
 
     try:
         sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
-        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        # No SO_REUSEADDR: we intentionally want only one worker to bind.
+        # Other workers receive EADDRINUSE and skip cleanly.
         sock.bind(('0.0.0.0', port))
         sock.settimeout(1.0)
         _sock = sock
+        print(f'routermon: UDP syslog receiver bound on port {port}', flush=True)
         logger.info('routermon: UDP syslog receiver bound on port %d', port)
     except OSError as exc:
         if exc.errno == errno.EADDRINUSE:
             logger.debug('routermon: port %d already bound (another worker), skipping', port)
         else:
+            import sys
+            print(f'routermon: failed to bind UDP port {port}: {exc}', file=sys.stderr, flush=True)
             logger.error('routermon: failed to bind UDP port %d: %s', port, exc)
         return
 

routermon/templates/routermon/dashboard.html

@@ -324,7 +324,7 @@ async function loadChart() {
   });
 
   // Top domains mini bar chart
-  const topData = {{ top_domains_json }};
+  const topData = {{ top_domains_json|safe }};
   const top10 = topData.slice(0, 10).reverse();
   domainsChartEl.setOption({
     tooltip: {trigger: 'axis', axisPointer: {type: 'shadow'}},